By Jonathan Moreland, founder of Insider Insights and author of Profit From Legal Insider Trading.

NEW YORK ( TheStreet) -- Which insiders are selling and buying chunks of stocks?

Below are lists of the top 10 open-market insider purchases and sales filed at the Securities and Exchange Commission Friday, May 6, 2011 as ranked by dollar value. Company executives and directors are in the best position to assess the attractiveness of their firms' shares, and here is how many of them are voting their wallets! Please note, however, that these are factual lists, not buy and sell recommendations. Dollar value is only one metric to assess the importance of an insider transaction.

Cerus (CERS) Corash Laurence M DIR 86,900 $241,617
Peoples Financial (PFIS) Wright Joseph T Jr DIR 5,000 $132,500
First Opportunity Fund (FOFI) Mildred B Horejsi Trust BO 18,068 $130,070
American National Insurance (ANAT) Dummer Arthur Oleen DIR 1,487 $118,811
Cincinnati Financial (CINF) Stecher Kenneth W CB,DIR 3,000 $92,670
MDC Partners (MDCA) Kauffman Scott L DIR 5,000 $82,300
MDC Partners (MDCA) Nadal Miles CB,CEO
5,000 $78,900
Opko Health (OPK) Frost Phillip Md CEO,CB
20,000 $74,698
HMS Holdings (HMSY) Schwartz Bart M DIR 750 $57,270
Home Bancorp (HBCP) Maraist Michael P DIR 2,500 $38,090
Intralinks Holdings (IL) TA Associates DIR,BO 330,000 $9,336,217
Liberty Global (LBTYA) SPO Advisory BO 204,552 $9,325,526
Under Armour (UA) Plank Kevin A PR,CEO
138,150 $8,976,378
Valmont Industries (VMI) Robert B Daugherty Charitable Foundation BO 49,500 $5,042,129
MSC Industrial Direct (MSM) Jacobson Mitchell DIR,BO 56,019 $3,978,388
MetroPCS Communications (PCS) Ta Associates Inc DIR 200,000 $3,540,690
Under Armour (UA) Plank J Scott VP,BD 46,875 $3,047,576
Red Hat (RHT) Whitehurst James M CEO,PR
66,661 $2,995,745
Lumber Liquidators Holdings (LL) Sullivan Thomas D CB,F
100,000 $2,543,080
Allegiant Travel (ALGT) Flynn Timothy P DIR 50,000 $2,342,155

Key to Titles:A=Assistant, AI=Affiliated Investor, AO=Accounting Officer, BD=Business Development, BO=Beneficial Owner, CAO=Chief Accounting Officer, CB=Chairman, CCO=Chief Compliance Officer, CEO=Chief Executive Officer, CFO=Chief Financial Officer, CIO=Chief Information Officer, CO=Compliance Officer, COO=Chief Operating Officer, CT=Controller, CTO=Chief Technology Officer, DIR=Director, EVP=Executive Vice President, F=Founder, FO=Financial Officer, GC=General Counsel, HR=Human Resources, IO=Information Officer, IR=Investor Relations, LO=Legal Officer, MD=Managing Director, O=Officer, OO=Operating Officer, PR=President, PT=Partner, REL=Relative of an insider, SEC=Secretary, SH=Shareholder, SO=Sales Officer, TO=Technology Officer, TR=Treasurer, TT=Trustee, VCB=Vice Chairman, VP=Vice President, X=Ex Officer or other title displayed.

Jonathan Moreland is the founder of, which produces a weekly newsletter and offers professional screening and alerting tools to analyze a proprietary, real-time insider data feed. He is also the principal of Insider Asset Management, a registered investment advisor in New York. Mr. Moreland has been analyzing insider data professionally for two decades and has been a contributor to since 2001. A fundamental analyst with an MBA in finance, Mr. Moreland long ago identified insider data as an excellent first screen to determine where to focus his research efforts. He is quoted frequently in the media for his insider analysis and stock recommendations stemming from it. He is also author of Profit From Legal Insider Trading.

Under no circumstances does the information in this column represent a recommendation to buy or sell stocks. While he cannot provide investment advice or recommendations, Moreland appreciates your feedback; click here to send him an email.